The reasons why babies always spit up are physiological factors, improper feeding, and pathological factors such as intussusception. 1. Physiological factors: the baby’s stomach is horizontal and the volume of the stomach is small, the cardia is not yet mature, when the baby drinks milk too quickly or cries when feeding, it can lead to the food in the stomach to return to the esophagus, the phenomenon of spitting up. 2. Improper feeding: the baby’s stomach volume is small, if the baby feeds too much milk at one time or feeds when the baby cries, does not pay attention to the posture when feeding and is in the horizontal position, and does not give the back patting to expel air in time, which leads to spitting up of the baby’s milk all the time. 3. Intussusception: Infants may show repeated vomiting, crying, and resolving jam-like stools, etc., and the vomit is milk or milk lumps. The baby is always spitting out milk, there may be other reasons, it is recommended to go to the hospital in time for relevant examinations, clear causes and active symptomatic treatment.